Nebraska and Oklahoma claim that Colorado's decision to legalize marijuana conflicts with the Controlled Substances Act and creates a "gap" in the federal drug control system. The complaint adds that "Marijuana flows from this gap into neighboring states, undermining Plaintiff States’ own 4 marijuana bans, draining their treasuries, and placing stress on their criminal justice systems."

In an amicus curiae brief, all nine former administrators of the Drug Enforcement Agency asked the court to look at the case. As the brief points out, "Colorado’s law contemplates acts by state officials and others that cannot be carried out without violating federal law."

Individuals can debate whether or not marijuana is dangerous, but the fact of the matter is that the Supreme Court hasn't dealt with the legality behind state laws' allowance of recreational marijuana.

As marijuana becomes legal in more states across the country, it's a question the Supreme Court may be forced to answer. The map below shows the spread of legalization, from medical CBD oils to recreational use.

The progression of marijuana legalization across the country. Yellow states have a total ban on the substance, light green states allow oil derived from marijuana for medical treatment, medium green states allow all forms of marijuana for medical treatment, and dark green states have legalized the substance recreationally. (GIF: Allison Shapiro)

Though the justices in the majority declined to explain their decision, Clarence Thomas and Samuel Alito voiced a dissenting opinion, explaining that they believe it to be the court's responsibility to hear the case since disputes between states are exclusively decided by the Supreme Court.

Officials from Nebraska and Oklahoma say they will continue pursuing the matter. "Today, the Supreme Court has not held that Colorado's unconstitutional facilitation of marijuana industrialization is legal," said Nebraska Attorney General Doug Peterson, "and the Court's decision does not bar additional challenges to Colorado's scheme in federal district court."

But judging by the rapid spread of pro-pot legislation, it seems Nebraska and Oklahoma may be on the wrong side of history.